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Patented May 4, 1926.

UNITED STATES PATENT OFFICE.

LOBIN B. SEBBELL, OI AKRON, OHIO, ASSIGNOR TO THE GOODYEAR TIRE & RUBBERCOMPANY, OI AKRON. OHIO, A CORPORATION OF OHIO.

METHOD VULGANIZI'N'G OAOUTOHOUC AND PRODUCT PRODUCED THEREBY.

Io Drawing. Original application filed February 9, 1924, Serial No.891,854. Divided and this application Med December 28, 1925. Serial No.77,411.

My invention relates to methods of vulcanizing rubber and rubbercompounds, and it has, for its primary object, the provision of methodsof vulcanization which shall insure products of high quality, especiallyadapted for the construction of various rubber articles, and inparticular, pneumatic tire casings.

It is well-known, of course, that accelerators are very desirable inproducing vulcanized rubber possessing suitable characteristics to adaptit for the manufacture of many rubber articles, of which pneumatic tirecasings form an outstanding example...

The accelerators are employed, not only as catalysts, but also to obtaincertain desired physical properties in vulcanized rubber compounds,which will enhance their value 1n many appllcatlons. For example, someaccelerators are especially deslrable because they impart such physicalcharacteristics to the vulcanized compound that it ages exceptionallywell, which is a desirable quality when it is employed in a great manycapacities, particularly in rubber tires. Other accelerators impartother outstanding characteristics, which it is especially desired tosecure. It will be apparent, then, that although there are a number ofaccelerators now known to the art, nevertheless each has its desirablefeatures, and may be especially selected with a view to producing afinal product which is particularly adapted for a certain use. 7

The present invention is primarily concerned with the disclosure of anumber of accelerators of such character as to insure a vulcanizedrubber product that is susceptible of general application.

It has been found, from extensive experimentation, that thiodiazoles aredesirable 0 accelerators for general application. The

accelerators may be broadly designated as compounds of pentacyclicformation, containing two carbon atoms, two nitrogen atoms and onesulfur atom, with a. mcrcapto group joined to one of the carbon atoms.

enerlc claims to this class of compounds are made in copendingapplication No. 691,-

854, filed February 9, 1924, while the present case, which is a divisionthereof, is restricted in scope to certain species, as will appear froma perusal of the claims.

Certain of the compounds may be somewhat more specifically indicated bythe following structural formula:

which is numbered in accordance with the more modern form ofnomenclature. In the latter formula, .if R is a henyl group, theresulting compound is designated as 3-phenyl-5-mercapto-l-24-thiodiazole.

be embodied in a. vulcanizing process, the following ingredients may beadmixed in the proportions .set forth. j

Parts.

Rubber; Zinc oxide 2.5 Sulfur .'L 33-phenyl-5-mercapto-1-2-4*thiodiazole .5

accelerator is employed, either of which will serve as an activator forthe accelerator, and

consequently increase its power to hasten the vulcanizingprocess. Suchactlvators are preferably mixed with the accelerator to form a physicalcombination therewith. Metallic salts may also be employ ed to advantagewith the accelerator as activators therefor, such salts being mixed withthe ac- V, celerator in-the same manner as the metalllc oxides. Examplesof such metalhc salts are As 4 'an example of how the latter compoundmay 3. A method of vulcanizing caoutchouc that comprises admixingcaoutchouc with a vulcanizing agent, incorporating in the mix a salt of3-para-t0lyl-5-mercapto-l-2-4- thiodiazole, adding an activator thereto,and subjecting the mixture to heat.

4. A methodof vulcanizing caoutchouc that comprises admixing caoutchoucwith a vulcanizing agent, incorporating in the mix a bivalent salt of3-para-tolyl-5-mercapto- 1-2-4-tl'1iodiazole, adding an activatorthereto, and subjecting the mixture to heat.

A. method of vulcanizing caoutchouc that comprises admixing cnoutchoucwith a vulcanizingagent, incorporating in the mix the zinc salt of3-para-tolyl-o-mercapto-1- 2-4-thiodiaz0le, adding an activator thereto,and subjecting the mixture to heat.

6. A vulcanized caoutchouc product formed by the reaction of caoutchouc,a vulcanizing agent, an activator, and3-paratolyl-5-mercapto-l-2-4-thi0diaz0le.

7. A vulcanized c-aoutchouc product formed by the reaction ofcaoutchouc, a vulcanizing agent, an activator, and the zinc salt of acompound having the general formula:

jjjzysn.

signed my name.

LORIN B. SEBRELL.

